VMS Help MACRO, VAX MACRO Assembler, Instructions, BITx  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Purpose:        Test a set of bits for all zero
    Format:         opcode mask.rx,src.rx
    Operation:      tmp = {src AND mask}
    C. Codes:       N = {tmp LSS 0}, Z = {tmp EQL 0}, V = 0, C = C
    Exceptions:     None
    Opcodes:        93    BITB     Bit test byte
                    B3    BITW     Bit test word
                    D3    BITL     Bit test long
    Description:    mask is ANDed with src. Both operands are unaffected.
                    The only action is to affect the condition codes.